diff --git a/docs/bib/ref.bib b/docs/bib/ref.bib
index c43f3d2..86fd6ec 100644
--- a/docs/bib/ref.bib
+++ b/docs/bib/ref.bib
@@ -156,7 +156,6 @@ @book{Press2007
    journal = {Sample page from NUMBERICAL RECIPES IN C},
    publisher = {Cambridge University Press},
    title = {Numerical Recipes 3rd Edition: The Art of Scientific Computing},
-   publisher = {Cambridge University Press},
    volume = {1},
    year = {2007},
 }